Here is one trick to greatly speedup asp.net compiler. First of all, assume you have enough RAM to give about 512Mb for this. RAM is cheap, so you always can visit store and buy it. And your time is priceless. 

Idea is in creating RAM drive and pointing asp.net compiler temp there. To create RAM drive you need to download following free software

http://www.ltr-data.se/opencode.html#ImDisk

IMDisk - awesome thing. Install it.

Now create ramdrive.cmd somewhere ( for example c:\ramdrive.cmd ) with following content

imdisk -a -s 512Mb -m R: -p "/fs:ntfs /q /y"  

create a shortcut and add it to Startup

Now everytime you start PC you'll see quick console window and you'll got a new drive "R"

Ok. Now you need to change your temp settings

Edit this file: C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\CONFIG\web.config  

( I assume that you've Windows installed in C:\Windows . Change path if it's different )

 In this file you need to add attribute to <compilation> tag

After change it should look like this: 

        <compilation tempDirectory="r:/asp.net_temp" > 

That's all. Now you can build your asp.net projects much faster. You can try to point all windows Temp on that RAM drive, but I haven't gone this far yet. 

Mailenable is quite good Mail Server for windows. It has a free version ( and that's version works good if you don't need WebMail ).

Here is some code to add mailbox to PostOffice.

I know one thing that makes cranky all web developers who still support IE 6. Usually we can hope that soon IE 6 became history ( maybe Windows 7 will be so good... and everybody use it and new IE ). But yet many designers still support IE 6. Main trouble that IE does not cache CSS background images. And that's why you see "flicker" effect on reload of you well formed css sites. To get rid of this try to add this script somewhere in the HEAD section... 

[code=js]

try

{document.execCommand('BackgroundImageCache', false, true);}

catch(e)

{}[/code]

 This works for me.

ps: You can see this effect good in AJAX.NET Tabs control. http://www.asp.net/AJAX/AjaxControlToolkit/Samples/Tabs/Tabs.aspx

Recently faced the big problem with big files. Not so big, just needed to post files with size about 10-20MB to aspx page. With usage of quite standard control on the page.

Everybody know ( if not - I notice here ) that in web.config you have HttpRuntime settings. And one of these settings is  maxRequestLength .In theor, after adding of this line to web.config file everything should work fine.

 <httpRuntime maxRequestLength="100000"/>

But in fact you can face the problem of limit in IIS. And this is a pain in the ass. Because you need to edit Metabase.xml on server. Sometimes this can be impossible, but sometimes you can do this yourself or ask support. Here is some insturctions to make big files uploads work for you.

More...

Recently found one thing. Perhaps in docs for AJAX client or somewhere else was such line:

Sys.Application.notifyScriptLoaded(); 

You need to write this line at the end of your JS files. But this can cause the problems if you wish to re-use this code in non-ajax enviroment. For this better to use following line:

if (typeof(Sys) !== 'undefined')  Sys.Application.notifyScriptLoaded(); 

This makes things a bit better. Also, it answers another question - "Testing for defined variables in Javascript".  Sometimes I see the code like:

if( Sys )...  // And this will fail in case Sys is undefined. 

 That's all for now, it's summer. Everybody enjoy their resort life. But I'm still working.

Sometimes on websites with user content you can find some design issues because of their content. Actually, I'm about the stuff like

"Swimming*Skimboaring*AquaFitness*Snorkeling*Kayaking*Basketball*Archery*Volleyball*Soccer*Table Tennis*Mini Golf*Badminton*Rock Climbing* Kiteboarding*Fencing*Gymnastics*Yoga*Pilates*"

But we ( as developers want to get rid of such ugly stuff that moves across the bounds of area and can't be wrapped - because there are no white-space inside.

For this I just written force wrap function. It is quite simple, using regular expressions

[code=cs] protected static string ForceWrap(string aStr,int max)
        {
            Regex LongLine = new Regex(@"(?<long>\S{"+max.ToString()+",})");
            MatchCollection matches = LongLine.Matches(aStr); // find all matches of "Long Strings" //
            if (matches.Count > 0)
            {
                StringBuilder sb = new StringBuilder(aStr);
               
                for (int i = 0; i < matches.Count; i++)
                {
                    string s = matches[i].Groups["long"].Value;
                    string origS = s;
                    int segments = s.Length / max;
                    for (int j = 1; j < (segments+1); j++)
                    {
                        int pos = j * max + (j-1);
                        s = s.Insert( pos , " "); // Insert Space //
                    }
                    sb.Replace(origS, s);
                }
                aStr = sb.ToString();
            }
            return aStr;
        }[/code] 

First parameter - the string you want to output, the second - max lenght is chars. Return value is new string with whitespace inserted if needed.

I think this is useful, but if there are something better, please let me know. 

Credit card numbers are full of magic. First of all not every 16 digit is CC number, but only by number you can know the issuer. So no need to place on the web form "Visa" / "MasterCard" radio button. Ok, so what's interesting. I found two great articles that helped me with this:
http://www.merriampark.com/anatomycc.htm and http://www.beachnet.com/~hstiles/cardtype.html .

And what now ? I just finished small helper class to validate Credit Cards. Here is the source.

[code=csharp]public enum CCType
    {
        VISA, MC
    }

    /// <summary>
    /// Credit card validation.
    /// Supports : VISA and MasterCard
    /// Reference: http://www.merriampark.com/anatomycc.htm
    /// Contains LUHN (mod 10) check
    /// by D.S.
    /// http://aspnetcafe.com
    /// </summary>
    public class CreditCardValidator
    {
        protected string _CardNumber = "";

        public CreditCardValidator(string aCardNumber)
        {
            _CardNumber = aCardNumber.Replace(" ","").Replace("-","");
            ProcessValidation();
        }

        protected bool _IsValid;

        public bool IsValid
        {
            get { return _IsValid; }
            set { _IsValid = value; }
        }

        private CCType _CardType;

        public CCType CardType
        {
            get { return _CardType; }
            set { _CardType = value; }
        }
       
        protected void ProcessValidation()
        {
            bool passRegEx = false;
            bool passIssuer = false;
            bool passLuhn = false;
            IsValid = false;

            do
            {
                // Reg Ex check //
                Regex RegExNumber = new Regex(@"(?<firsttwo>(?<firstone>\d)\d)\d{11,14}");
                Match m = RegExNumber.Match(_CardNumber);
                passRegEx = m.Success;
                if (!passRegEx) break;
                string number = m.Groups[0].Value; // only digits //
                string firstNum = m.Groups["firstone"].Value;
                int firstTwoNum = int.Parse(  m.Groups["firsttwo"].Value );
                passIssuer = (firstNum == "4") || ((firstTwoNum >= 51) && (firstTwoNum <= 55));
                if (!passIssuer) break;
                if (firstNum == "4") CardType = CCType.VISA;
                if ((firstTwoNum >= 51) && (firstTwoNum <= 55)) CardType = CCType.MC;
                // Now make Luhn check //
                passLuhn = LuhnCheck(number);
                if (!passLuhn) break;
                //
                IsValid = true;
            } while (false);          
        }

        /// <summary>
        /// Performs mod 10 check
        /// </summary>
        /// <param name="cardNumber">Card Number with only numbers</param>
        /// <returns></returns>
        protected bool LuhnCheck(String cardNumber)
        {
            int sum = 0;
            int digit = 0;
            int addend = 0;
            bool timesTwo = false;

            for (int i = cardNumber.Length - 1; i >= 0; i--)
            {
                digit = int.Parse(cardNumber.Substring(i, 1));
                if (timesTwo)
                {
                    addend = digit * 2;
                    if (addend > 9)
                    {
                        addend -= 9;
                    }
                }
                else
                {
                    addend = digit;
                }
                sum += addend;
                timesTwo = !timesTwo;
            }

            int modulus = sum % 10;
            return (modulus == 0);
        }
    }[/code]

The code is quite simple. But works good for me. I'm not providing you with a sample application, you know there are my credit card number :)

Check the articles at the top of the page if you want to know how it's works. And what is Mod 10 check.

There is a thing that allows you to point user on the right place on page after postback. The secret is not a secret - just javascript focus() function called. But how to make this right using the ASP.NET framework. It's not a big deal... there are a function for this:

[code=C#]Page.SetFocus(top.ClientID);[/code]

And this works good in case of PostBack. But what going on if you are using partial postback ( using update panel of Ajax extensions )?
This does not work any more. But works this.

[code=C#]ScriptManager.GetCurrent(Page).SetFocus(top);[/code]

What also can you find useful ? Hmm...  sometimes it does not work. Why? 90% that are you trying to set focus on the Control that does not receive focus in browser.
Don't try to focus a Label. Focus Anchor tag if you need to focus a place on your page.

Usually peoples try to include javascript functions that do this job, but I think that this way is better.

Sometimes we want to take one pair of aspx/aspx.cs files and copy into another.
If you really want to get new page (and the same for User Controls) remember to do the following after you copied page:

• Check the CodeFile and Inherits attributes of you Page/User Control
• Rename class inside aspx.cs or ascx.cs
• Change CodeFile and Inherits to the correct classes

All of this applies to VS 2005. Than does not automatically rename classes if you Copy/Paste files in solution explorer. And sometimes you can feel confused because of this.

IMHO, better not to copy files in solution explorer at all. And if you need to do this, maybe you have conceptual problems?